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Abstract INTRODUCTION: A major concern in the microbicide field is how long a microbicide remains active in the vagina without being absorbed and/or inactivated. Ideally a vaginal microbicide should remain active for an extended period of time following application. This is imperative, as infection might not occur at the time of intercourse but subsequently. In addition, prolonged activity of a microbicide may render the microbicide more acceptable by allowing women more flexibility with time of product use. METHODS: Fourteen women inserted 4 mL of Carraguard while being observed by the study clinician. The clinician thoroughly flushed the vagina with saline lavages at set time points following application. Lavage specimens were frozen and subsequently assayed for carrageenan content using an established colorimetric assay. In addition, specimens were assayed for Carraguard activity using an in vitro herpes simplex virus type 2 (HSV-2) plaque assay. A baseline lavage sample for each subject was used as a control. RESULTS: Although the amount of carrageenan in lavages taken at the same time varied among subjects, the results of chemical analysis indicated that carrageenan is detectable in all vaginal lavage samples collected at various time points. Interestingly, significant amounts of carrageenan were recovered from women who had a second follow-up lavage as well as lavages collected at 24 hours. The HSV-2 plaque assay showed that Carraguard retained activity at all time points, including those collected at 24 hours. CONCLUSIONS: These findings indicate that Carraguard is retained and remains active in the human vagina for at least 24 hours. This is not unexpected as the carrageenan is a very high molecular weight polymer and has been shown not to be systemically absorbed. The observation that two sequential saline lavages does little to change the amount of Carraguard that is recovered suggests that Carraguard is not easily flushed from the vagina even though it is very water soluble. Extended retention may be a consequence of a reservoir of Carrageenan between the vagina and ectocervix or that Carraguard is bound to the cervical/vaginal epithelium. Poster Session
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